Rather a dull movie until the ending
I saw this the first time when I was about 12 years old. I didn't think much of it back then and now as an adult I thought I would give the movie a second go.
After 50 minutes in I was so bored of it. Nothing really much happens except Joan Crawford looking and acting crazy, but by then I had already worked out the twist.
The movie has a good story but it's executed (if you pardon the pun) too slowly and the script isn't very good.
I'd say this movie is overrated. I'd give it a generous 4/10. I won't be watching it again.